Multiple spark plug per cylinder ignition system



Oct. 29, 1968 KAY lsHlBAsl-u MULTIPLE SPARK PLUG PER CYLINDER IGNITION SYSTEM 3 Sheets-Sheet l Filed Aug. 23, 1966 Oct. 29, 1968 MULTIPLE vSPARK PLU Filed Aug. 25, 1966 KAY ISHIBASHI G PER CYLINDER IGNITION SYSTEM E Sheets-Sheet 2 INVENTOR KAY Z'Isw/aAs/w #fram/Ems' Oct. 29, 1968 KAY ISHIBASHI 3,407,797

MULTIPLE SPARK PLUG PER CYLINDER IGNITION SYSTEM Filed Aug. 25, 1966 3 SheetS-Sheet 5 VY-* l m 4 /56 HMH@ /f-f L@ f2- W l2 /z'f /7 l2 F I GJ l FIG; l2 l FfGJ INVENTOR KAY .ZIs'f//As/f/ L @ahw Afro/mens' United States Patent O 3,407,797 PviULTiFIJE SPARK PLUG PER SYINDER IGNTIUN SYEiTEh'i Kay ishibashi, 2277 237th St., Torrance, Caiii. 965m Filed Ang. 23, 19%, Ser. No. 574,466 i Claims. (Cl. 1215-4143) ABSTRACT F THE UESCILGSURE An ignition system for an internal combustion engine and including a pair of spark plugs disposed in igniting relationship with a cylinder. Electrical circuitry connects the ignition system coil with the individual spark plugs on successive revolutions of the engine to provide a cooling period for each of the plugs as the other plug is being tired.

The present invention relates to improvements in ignition systems for internal combustion engines and, more particularly, to a novel ignition system inciuding a plurality of spark plugs for each cylinder ot an associated internal combustion engine.

Spark plug life and spark plug maintenance are matters of general concern to most operators of vehicles powered by internal combustion engines and are matters of special concern to those who own and operate vehicles powered by two-cycle engines. In this regard, it is a well known fact that the higher the operating speed of an internal combustion engine, the more rapid the deterioration of the spark plugs in the engine. Since the firing rate of the spark plugs increases linearly with increasing engine speed, it is logical to expect the spark plugs to deteriorate in a linear manner as engine speed increases. Likewise, it is logical to expect the spark plugs in two-cycle engines to wear twice as rapidly as spark plugs in ffour-cycle engines when operating at the same engine speed. In practice, this is not the case at all. In ifact, the rate of spark plug rwear with increasing engine speed is more exponential than linear `and the spark pulgs in two-cycle engines wear many times faster than like spark plugs in four-cycle engines.

The reasons for exponential spark plug wearing rates is not completely understood. However, it is believed that as engine speed increases, the spark plugs have less time to cool between consecutive rings than at lower engine speeds. The hotter the spark plugs, the more rapidly they wear and become fouled with carbon and other foreign particles.

Since the spark plugs in two-cycle engines iire twice as often as spark plugs in four-cycle engines, the two-cycle engine spark plugs have even less time to cool than do their four-cycle engine counterparts. Therefore, spark plugs in two-cycle engines wear out many times faster and require more frequent servicing than like plugs in four-cycle engines.

The problems of rapid spark plug wear and requirements for frequent spark plug maintenance are common to all commercially available ignition systems. Accordingly, it is an object of the present invention to provide an improved ignition system wherein the spark plugs have -a relatively long life lwhen compared with spark plugs in conventional ignition systems.

Another object of the present invention is to provide an ignition system orf the foregoing character in which spark plugs require infrequent servicing when compared with conventional ignition systems.

A further object of the present invention is to provide an ignition system which includes a plurality of spark plugs per cylinder and means for tiring the spark plugs in succession to allow the spark plugs a cooling period be- 3,457,797 Patented Oct. 29, 1968 ICC tween consecutive operations sutcient to materially increase the operating life of the spark plugs.

It is another object of the present invention to provide an ignition system of the foregoing character wherein the spark plugs for each cylinder are fired consecutively at relatively high engine speeds and simultaneously at relatively low engine speeds to insure that the engine will start and operate eiiiciently at low speeds despite the occurrence of defects in one or more of the spark plugs for each cylinder which would prevent the engine from starting if used alone and which would not otherwise allow the engine to run at low speeds.

A still further object of the present invention is to provide an ignition system of the foregoing character which is specially useful in two-cycle internal combustion engines.

The foregoing as well as other objects and advantages of the present invention may be more clearly understood by reference to the folowing detailed description when considered with the drawings which, by way of example only, illustrate particular ignition systems incorporating features and advantages of the present invention.

In the drawings:

FIGURE l is a side view illustrating the exterior of an engine and an ignition system incorporating the features of the present invention;

FIGURE 2 is a sectional view taken along the line 2 2 in FIGURE 1 illustrating the internal construction of a distributor in the ignition system;

FIGURE 3 is a fragmentary view taken along the line 3-3 in FIGURE 2;

FIGURE 4 is a fragmentary sectional View taken along the line d-t in FIGURE 2;

FIGURE 5 is a sectional view taken along the line 5-5 in FIGURE 2;

FIGURE 6 is a sectional view taken along the line 6 6 in FIGURE 4;

FIGURE 7 is a schematic of the ignition system illustrated in FIGURE 1 including one cylinder having two spark plugs extending therein, the internal combustion engine associated with the ignition system operating at a relatively low speed and the ignition system cooperating therewith to simultaneously fire both spark plugs in the cylinder;

FIGURE 8 is a schematic representation of the ignition system of FIGURE 7 wherein the associated internal combustion engine is operating at a higher speed and the ignition system is cooperating therewith to alternately lire the spark plugs in the cylinder;

FIGURE 9 is a schematic representation of an ignition system similar to FIGURE 7 including two cylinders, each having two spark plugs therein, the engine associated with the ignition system operating at a relatively low speed whereby the spark plugs in each cylinder tire simultaneously upon the transfer of energy to the cylinders by the distributor of the ignition system, the distributor being designed such that the spark plugs will re alternately at higher engine speeds;

FIGURE 10 is a schematic representation of an ignition system including two spark plugs for each of four cylinders in the associated internal combustion engine, the engine operating at a relatively low speed whereby the spark plugs in each cylinder fire simultaneously as electrical energy is transferred thereto by the distributor in the ignition system, the distributor being designed such that the spark plugs in each cylinder will tire alternately at higher engine speeds;

FIGURE l1 is a fragmentary sectional view similar to FIGURE 3, illustrating a simplied form 'of the distributor in the ignition system adapted to alternately fire the spark plugs in each cylinder of the associated engine;

FIGURE 12 is a sectional view taken along the line 12--12 in FIGURE l1;

FIGURE 13 is a schematic of an ignition system incorporating the distributor of FIGURES 11 and l2, the ignition system including one cylinder having two spark plugs extending therein and the distributor being adapted to alternately lire the spark plugs in the cylinder, the distributor rotor being in a position to cause one of the spark plugs to fire;

FIGURE 14 is a schematic similar to FIGURE 13 with the rotor being in a position to cause the other of the spark plugs to fire; and

FIGURE 15 is a schematic representation of an ignition system including two spark plugs for each of four cylinders in an associated internal combustion engine, the distributor of the system being designed such that the spark plugs in each cylinder will be tired alternately.

Generally speaking, the ignition system of the present invention is denoted as a multiple spark plug per cylinder ignition system. This means that in the ignition system two or more spark plugs may be incorporated in the cylinders Aof the associated internal combustion engine. In the forms of the ignition system illustrated in the drawings, two spark plugs are included for each cylinder. However, if desired, a greater number of spark plugs may be incorporated Without departing from the spirit of the invention and the same basic structural principles may be employed to implement the features of the invention.

In addition, in the ignition system of the present invention, the distributor is designed to successively re the spark plugs of each cylinder when the associated engine is operating at relatively high speeds and is designed to simultaneously fire the spark plugs in each cylinder at relatively low engine speeds.

Therefore, at high engine speeds, the ignition system provides each spark plug with a rest time between successive firings which is sufficient to allow the plug to cool and thereby materially decrease its rate of deterioration, when compared with a like plug in a conventional ignition system.

By simultaneously firing the plugs at low engine speeds, the ignition system insures reliable starting of the engine despite possible Weaknesses and defects in one of the spark plugs for each cylinder which if tired individually might prevent the engine from starting. Also even through one of the plugs in each cylinder may be defective, the simultaneous firing of both plugs allows the engine to operate at low engine speeds at least to the extent that the operator of the vehicle is able to drive the vehicle to a nearby garage for servicing or replacement ofthe defective plug or plugs.

In FIGURES 1-8, the internal combustion engine is represented generally by the numeral I@ and is a twocycle engine having one cylinder 12. The ignition system for the engine 1t) is represented generally by the numeral 14 and includes two spark plugs 16 and 18 extending into the cylinder 12, a distributor Ztl, a coil 22, and a wire 24 from the coil to the distributor as well as wires 26 and 28 from the distributor to the spark plugs 16 and 1S.

Generally speaking, electrical energy from the coil 22 is transferred to the distributor which in turn selectively distributes the electrical energy to the wires 26 and 28 and hence to the spark plugs 16 and 18 to fire the spark plugs simultaneously when the engine 11B is operating at a low speed (FIGURE 7), or alternately when the engine is operating at relatively high engine speeds (FIGURE 8).

More particularly, the distributor includes a housing 30 supporting a rotor 32, a reduction gear unit 34, an electrical contact mechanism 36, and an electrical circuit unit 38. The housing 3l) is formed from tive rectangular plates 40, 42, 44, 46 and 48 held tightly together by four corner bolts 50 and nuts 52 screwed tightly onto threaded ends of the bolts.

A :chamber S4 is formed within the housing 30 by ad- 54 houses the reduction gear unit 34 including relatively small and large spur gears 641 and 62. The large spur gear 62 is connected by a pin 64 to a rotor shaft 66 of the rotor 32 while the small spur gear 60 is connected by a pin 68 to a drive shaft 70 extending rearwardly from the distributor for connection to the crank shaft 72 of the engine 16.

The drive and rotor shafts and 66 are supported in a horizontal plane for rotation about their longitudinal axes by bearing units 74, 76, 78 and 80.

The bearing unit 74 includes an inner race S2 on the shaft 79, an outer race 84 secured in the hole 86 in the plate 40, and a plurality of ball bearings 88 captured between the inner and outer races.

The bearing unit 76 includes an inner race 90 on an end of the shaft 76, an outer race 92 secured within a circular cavity 94 in the plate 44, and a plurality of ball bearings 96 captured between the inner and outer races.

The bearing unit 78 includes an inner race 98 on a rear end of the rotor shaft 66, an outer race 100 secured tightly within the circular cavity 102 in the plate 40, and a plurality of ball bearings 102 captured between the inner and outer races.

The bearing unit 36 includes an inner race 106 on the rotor shaft 66, an outer race 108 secured tightly within a hole 110 in the plate 44, and a plurality of ball bearings 112 captured between the inner and outer races.

Annular grease seals 114, 116, 118, and are seated between the inner and outer races of the bearing units 74 and 86 on opposite sides of the ball bearings 88 and 116 to prevent grease within the chamber S4 from leaking out of the housing 36. In this regard, the top of the housing 34B and the plate 42 includes a threaded hole 124 for receiving a plug 126. The plate 42 also includes a top hole 12S for receiving a breather tube 130 to allow air to escape .from the chamber S4 as grease is poured through the opening 124 and into the chamber 54. When the chamber is full of grease, the plug 126 is secured tightly within the hole 124. The grease provides lubrication for the reduction gear unit 34 upon a turning of the crank shaft '72 and an operation of the engine 10.

As the crank shaft 72 turns, the spur gear 60y drives the spur gear 62 and the rotor shaft 66. Since the spur gear 62 is much larger than the spur gear 60, the rotor shaft turns at an angular velocity much less than the angular velocity of the crank shaft. For the two-cycle engine 10 and the ignition system 14 including two spark plugs per cylinder, the gear reduction unit 34 is constructed to provide a two-to-one gear reduction. Therefore, the rotor shaft 66 turns with one-half the angular velocity of the crank shaft 72. As will be described hereinafter, this allows the spark plugs 16 and 18 to be alternately tired when the engine 1t) is operating at a high speed. If the engine 11B were a four-cycle engine, the gear reduction unit 34 would be designed to provide a fourto-one reduction. If a greater number of spark plugs were incorporated in the cylinder 12, the gear reduction unit 34 would be constructed to provide the still higher gear reduction necessary for firing each of the spark plugs in succession upon a turning of the rotor shaft 96.

In addition to the rotor shaft 66, the rotor 32 includes a rotor cap 122 seated on an enlarged, hexagonal, forward end portion 124 of the rotor shaft. The rotor cap 122 is thus adapted to turn With the rotor shaft 66 Within a cavity 126 dened by circular, aligned holes 128 and 130 in the plates 46 and 48 of the housing 30.

The cavity 126 is closed by a cup-shaped outer cap 132 having an annular llange portion 134 adapted to t tightly into the cavity. An O-ring 136 is seated within an annular recess 138 in the outer surface of the flange 134 and in arcuate recesses 140 in the periphery of the holes 128 and 139 of the plates 146 and 148 to tightly seal the cavity 126 and prevent foreign particles from entering the cavity and possibly interfering with the operation of the distributor.

In addition to sealing the cavity 126, the outer cap 132 provides terminal support for the ends of the wire 24 and of wires 26 and 28 remote from the coil 22 and the spark plugs 16 and 18. The support of the wire 24 is most clearly illustrated in FIGURE 3. As represented, the cap includes a side hole 142 having a metal sleeve 144 stationed therein, The side hole 142 and the metal sleeve 144 are adapted to tightly receive and grip the end of the wire 24 having a metal cap 146 thereon. The metal cap 146 makes electrical contact with the sleeve 144 to electrically connect the sleeve to the wire 24 and hence to the coil 22.

As also represented most clearly in FIGURE 3, the side hole 144 communicates with a smaller hole 148 terminating in a cross hole 150 coaxial with the rotor shaft 96. The holes 148 and 150 receive coil springs 152 and 154 of the electrical circuit unit 38, which are compressed to tightly engage each other. The spring 152 makes electrical contact with the sleeve 144 while the spring 154 presses a metal tip member 156 inwardly against the electrical contact mechanism 36 in the distributor 20.

As most clearly illustrated in FIGURE 4, the end support provided for the wires 26 and 28 in the outer cap 132 comprises diametrically opposite side openings 158 and 160. Metal sleeves 162 and 164 are stationed within the side holes 158 and 160 and are adapted to tightly receive the metal capped ends of the wires 26 and 28 and to make electrical contact therewith.

The spatial relationship of the ends of the wires 24, 26 and 28 is most clearly illustrated in FIGURE 6. As represented, the inner face of the outer cap 132 includes diametrically opposite, arcuate slots 166 and 168 exposing the metal sleeves 164 and 162, respectively. The arcuate slots 166 and 168 thus provide means for selectively exposing the ends of the wires 26 and 28 and hence the associated spark plugs `16 and 18 to the electrical contact mechanism 36 as the rotor 32 turns in response to operation of the engine 10. This provides for the selective distribution of electrical energy emanating from the coil 22 to re the spark plugs 16 and 18 as the rotor turns within the housing 30.

To provide for the selective distribution of electrical energy, the electrical contact mechanism36 is carried by the rotor cap 122 and as the rotor cap turns selectively transfers electrical energy to the ends of the wires 24 and 26 to re the associated spark plugs 16 and 18. The electrical contact mechanism 36 is most clearly illustrated in FIGURES 2, 3 and 4 and is diagrammatically represented in FIGURES 7, 8, 9 and l0.

As represented, the electrical contact mechanism 36 includes two flat metal arms 170 and 172 mounted in a diametric channel 173 in the forward face of the rotor cap 122. The arm 170 is xedly stationed rearward of the arm 172 with a bent tip end 174 extending forwardly from and radially beyond the rotor cap. The arm 172 is adapted to slide radially inwardly and outwardly along the arm 170 in electrical contact therewith and includes an outer tip portion 176 adapted to extend outwardly beyond the rotor cap the same distance as the tip 174. Accordingly, with a turning of the rotor cap, the tip portions 174 and 176 are adapted to describe the same circle and to pass immediately behind the arcuate slots 166 and 168 inthe rear face of the outer cap 132.

As illustrated in FIGURES 3 and 4, tip member 156 is continuously urged by the spring member 150` into tight electrical contact with the arm 170 to provide a direct path for electrical energy from the coil 22 to the electrical contact mechanism 36. Accordingly, with the tip portions 174 and 176 describing the same circle and being diametrically opposite each other, when electrical energy is transferred from the coil 22 to the electrical contact mechanism 36, such energy is selectively distributed to both of the spark plugs 16 and 18 when the tip portions pass immediately behind the slots 166 and 168-- energy arcing from the tip portions to the ends of the wires 26 and 28 connected to the spark plugs.

As previously indicated, such simultaneous transfer of energy to the spark plugs causes the spark plugs 16 and 18 to tire simultaneously and occurs when the engine 10 is operating at a relatively low speed. When the engine is operating at a high speed, however, the spark plugs 16 and 18 are alternately tired. To accomplish this, the electrical contact mechanism 36 includes an angular velocity sensitive device 178 for moving the arm 172 along the arm with changes in the angular velocity of the rotor cap 122. In particular, when the rotor cap 122 is turning at a relatively low angular velocity, the tip portion 176 extends radially beyond the rotor cap 122 and upon a turning of the rotor cap, the tip portions 174 and 176 simultaneously pass over the ends of the wires 26 and 28 to simultaneously re the spark plugs 16 and 18 upon a transfer of energy from the coil 22 (see FIGURE 7). As the angular velocity of the rotor cap 122 increases, however, the velocity sensitive device 178 moves the arm 17 6 from the circle described by the tip 174. This condition is illustrated most clearly in FIGURE 8. Under such conditions, the tip portion 176 does not move over the arcuate slots 166 and 168 and no energy is transferred by the tip portion 176 to the spark plugs 16 and 18. Therefore, as the rotor turns, energy is only transferred from the tip potrion 174 to alternately lire the spark plugs 16 and 18 as the tip portion moves in succession over the ends of the wires 26 and 28.

The angular velocity sensitive mechanism 178 is illustrated most clearly in FIGURE 3 and includes a bent arm 188 connected to 4a pivot pin 182 secured to the forward face of the rotor cap 122. One end of the bent arm deiines a :finger 184 extending into a side slot 186 in the arm 1'72, while an opposite end of the bent arm is connected to a counterweight 188. A leaf spring 198 secured to the rotor cap continuously urges the counterweight 188 toward the axis of the rotor shaft 66 to cause the linger 184 to move the arm 172 outwardly along the arm 170 to position the tip portion 176 slightly beyond the outer edge of the rotor cap 122. As the angular velocity of the rotor cap increases, however, the counterweight 18S is forced outwardly away from the axis ofthe rotor shaft 66 causing the bent arm 181) to slide the movable arm 172 inwardly along the arm 170 to produce :an alternate tiring of the spark plugs in the ignition system 14. As the rotational velocity of the rotor cap decreases, the leaf spring 190 again returns the movable arm 172 to its original position to again produce a simultaneous tiring of the spark plugs 16 and 18.

An additional feature of the distributor 20 is the ease with which the timing of the distributor operation may be adjusted. In particular, simply -by loosening the nuts 52 on the ends of the bolts 58', the outer cap 132 may be manually turned slightly in either a clockwise or counterclockwise direction. As the outer cap is turned, the angular position of the ends of the spark plug wires 26 and 28 is shifted relative to the tip member 156 carrying the electrical energy from the coil 22 to the electrical contact mechanism 36. In this manner, the timing of the distributor 2l) may be advanced or retarded as desired and then locked in a set position by retightening the nuts 52.

Ignition systems employing the principles ofthe ignition system 14 and including two and four cylinders are diagrammatically represented in FIGURES 9 and 10'. In fact, the same essential arrangement is employed except that the outer cap 132 of the distributor includes side openings for receiving the ends of wires from the pairs of spark plugs in each cylinder-the ends,` being diametrically opposite each other and equally spaced from the ends of the other spark plug wires. The balance of the ignition system is as previously described, and the ignition systems of FIGURES 9 and 10 operate in the same manner as the system illustrated in FIGURES 7 and 8 wherein the spark plugs for each cylinder are simultaneously tired at relatively low engine speeds tand are alternately tired at relatively high engine speeds to provide a rest time for the spark plugs whereby the spark -plugs cool and do not deteriorate nearly as rapidly as like spark plugs in conventional ignition systems.

While a particular form of ignition system has been described in some detail herein, changes and modifications may be made therein without departing from the spirit of the invention. For example, the distributor 20 may be designed to always alternately re the spark plugs regardless of the speed of the associated vehicle, thereby eliminating the angular velocity sensitive mechanism 178 and the slidable arm 172. Such a structural arrangement for the distributor 20 is illustrated most clearly in FIGURES 1l and l2 wherein like `reference numerals are utilized to indicate the same elements as previously described in connection with FIGURES 1-10. Due to the direct similarity between the structure of FIGURES l1 and 12 and that previously described, reference to the detailed description of FIGURES 2, 3 and 4 will provide a complete understanding of the structure, features and advantages of the simplified structure of FIGURES 11 and 12.

The ignition systems incorporating the simplified distributor are diagrammatically illustrated in FIGURES 13 and 14 using a single cylinder 12 including two spark plugs 16 and 18. As represented, as the rotor turns, the electrical contact mechanism 35 -describes a circle to alternately move adjacent the ends of the wires Z6 and 28 from the spark plugs 16 and 18 to alternately distribute electrical energy thereto, causing the spark plugs to alternately lire on consecutive compression strokes in the cylinder. In this manner, irrespective of engine speed, the spark plugs are provided with a rest time suticient to allow the plugs to cool so that they do not deteriorate nearly as rapidly as like spark plugs in conventional ignition systems.

An ignition system employing the simplified distributot` and including four cylinders, each having two spark plugs, is illustrated diagrammatically in FIGURE 15. Thus arranged, the spark plugs in each cylinder tire alternately irrespective of engine speed to materially increase the useful life of the spark plugs.

In view of the foregoing as well as other modifications and changes which may be made in the present invention, it is intended that the invention be limited in scope only by the terms of the following claims.

I claim:

1. In an ignition system for an internal combustion engine:

a cylinder; y

a pair of spark plugs disposed in igniting relationship with said cylinder;

electrical circuitry means connected with the coil of said ignition system and with said spark plugs, said electrical circuitry including timing means coupled with the crankshaft of said engine for alternately firing said spark plugs to provide a cooling period for each of said plugs while the other of said plugs is being tired.

2. The combination set forth in claim 1 wherein said timing means includes:

a pair of contacts; Y

a contact mechanism including a iirst arm `formed with a first contact portion :and a second arm formed with a second contact portion, said second arm having a retracted position with said second contact portion disposed to clear said contacts as said mechanism is rotated and an extended position with said second contact portion disposed for sequentially engaging said contacts as said mechanism is rotated;

control means for selectively moving said second arm from said retracted position to said extended position.

3. The combination set forth in claim 2 wherein said control means includes:

a rotor cap supporting said contact mechanism and coupled with said crankshaft for rotation thereby;

a counterweight pivotally connected to said rotor cap and including a finger engaging said second arm `for ymoving said second arm into said retracted position when said engine reaches a predetermined speed.

4. The combination set forth in claim 3 wherein said control means includes:

means biasing said second arm into said retracted position.

References Cited UNITED STATES PATENTS 1,759,425 5/1930 Suekof 123-148' 2,465,080 3/1949 Fitzsimmons 123-148 2,643,275 6/1953 Saunders 123--148 LAURENCE M. GOODRIDGE, Primary Examiner. 

